1. Field of the Invention
The invention relates to an exercise apparatus, and more particularly to an elliptical exercise apparatus.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional elliptical exercise apparatus includes a frame unit 1, a crank wheel unit 2 disposed on the frame unit 1 and having two crank arms 201, and two link units 3 disposed respectively on left and right sides of the frame unit 1. Each link unit 3 includes a pedal rod 301 connected pivotally to one of the crank arms 201, a handle 302 connected pivotally to the frame unit 1, a link rod 303 connected pivotally to a central section of the pedal rod 301 and a bottom end of the handle 302, a support roller 304 connected to the frame unit 1 and in rollable contact with the central section of the pedal rod 301, and a pedal plate 305 disposed on a rear end of the pedal rod 301. Through such a connection, the user's feet can travel along a generally vertically oriented elliptical path during exercise.
However, since the support roller 304 of each link unit 3 is connected to the frame unit 1 at a fixed position, a distance (L) from an axis of rotation of the support roller 304 to an axis of rotation of the crank arms 201 is fixed. This results in the amplitude of upward and downward motion of the pedal plate 305 being also fixed. The size of the elliptical path traveled by the pedal plate 305 is therefore also fixed and cannot be varied. In this case, the user can only exercise the muscle group on his/her lower half body, but not the muscle group on his/her upper half body.